How to apply outer limit offset and filters in the subquery to avoid grouping over the complete table used in...
0
I have the following legacy tables:
employee
------------------------------------
| employee_id | name
------------------------------------
| 1 | David
| 2 | Mathew
------------------------------------
payroll
-------------------------------------
| employee_id | salary
-------------------------------------
| 2 | 200000
| 3 | 90000
-------------------------------------
I want to get the following data, after joins and filters:
-----------------------------------------------------------
| address_id | employee_id | address
-----------------------------------------------------------
| 1 | 2 | street 1, NY
| 2 | 2 | street 2, DC
------------------------------------------------------------
I have the following query:
SELECT employee_id, salary, address_arr
FROM employee
LEFT JOIN payroll on payroll.employee_id = employee.employee_id
INNER JOIN
(
SELECT employee_id, ARRAY_AGG(address) as address_arr
FROM addresses
GROUP BY employee_id
) table_address ON table_address.employee_id = employee.employee_id
WHERE employee.employee_id < 1000000
LIMIT 100
OFFSET 0
Above query gives the desired output but is highly unoptimized as the GROUP BY operation occurs over the complete addresses table before being used for JOIN operation the outer query.
Kindly answer:
- How can we avoid the
GROUP BYoperation to occurs over the complete
addresses table by usingLIMIT OFFSETof the outer query? - Will the condition
WHERE employee.employee_id < 1000000be applied on subquery before or after theGROUP BYoperation in the inner query. If the condition is applied after theGROUP BY, how can we avoid that?
postgresql join postgresql-performance group-by subquery
asked 2 mins ago
nimeshkiranvermanimeshkiranverma
1012
New contributor
nimeshkiranverma is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
0
I have the following legacy tables:
employee
------------------------------------
| employee_id | name
------------------------------------
| 1 | David
| 2 | Mathew
------------------------------------
payroll
-------------------------------------
| employee_id | salary
-------------------------------------
| 2 | 200000
| 3 | 90000
-------------------------------------
I want to get the following data, after joins and filters:
-----------------------------------------------------------
| address_id | employee_id | address
-----------------------------------------------------------
| 1 | 2 | street 1, NY
| 2 | 2 | street 2, DC
------------------------------------------------------------
I have the following query:
SELECT employee_id, salary, address_arr
FROM employee
LEFT JOIN payroll on payroll.employee_id = employee.employee_id
INNER JOIN
(
SELECT employee_id, ARRAY_AGG(address) as address_arr
FROM addresses
GROUP BY employee_id
) table_address ON table_address.employee_id = employee.employee_id
WHERE employee.employee_id < 1000000
LIMIT 100
OFFSET 0
Above query gives the desired output but is highly unoptimized as the GROUP BY operation occurs over the complete addresses table before being used for JOIN operation the outer query.
Kindly answer:
- How can we avoid the
GROUP BYoperation to occurs over the complete
addresses table by usingLIMIT OFFSETof the outer query? - Will the condition
WHERE employee.employee_id < 1000000be applied on subquery before or after theGROUP BYoperation in the inner query. If the condition is applied after theGROUP BY, how can we avoid that?
postgresql join postgresql-performance group-by subquery
asked 2 mins ago
nimeshkiranvermanimeshkiranverma
1012
New contributor
nimeshkiranverma is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
0
0
0
I have the following legacy tables:
employee
------------------------------------
| employee_id | name
------------------------------------
| 1 | David
| 2 | Mathew
------------------------------------
payroll
-------------------------------------
| employee_id | salary
-------------------------------------
| 2 | 200000
| 3 | 90000
-------------------------------------
I want to get the following data, after joins and filters:
-----------------------------------------------------------
| address_id | employee_id | address
-----------------------------------------------------------
| 1 | 2 | street 1, NY
| 2 | 2 | street 2, DC
------------------------------------------------------------
I have the following query:
SELECT employee_id, salary, address_arr
FROM employee
LEFT JOIN payroll on payroll.employee_id = employee.employee_id
INNER JOIN
(
SELECT employee_id, ARRAY_AGG(address) as address_arr
FROM addresses
GROUP BY employee_id
) table_address ON table_address.employee_id = employee.employee_id
WHERE employee.employee_id < 1000000
LIMIT 100
OFFSET 0
Above query gives the desired output but is highly unoptimized as the GROUP BY operation occurs over the complete addresses table before being used for JOIN operation the outer query.
Kindly answer:
- How can we avoid the
GROUP BYoperation to occurs over the complete
addresses table by usingLIMIT OFFSETof the outer query? - Will the condition
WHERE employee.employee_id < 1000000be applied on subquery before or after theGROUP BYoperation in the inner query. If the condition is applied after theGROUP BY, how can we avoid that?
postgresql join postgresql-performance group-by subquery
asked 2 mins ago
nimeshkiranvermanimeshkiranverma
1012
New contributor
nimeshkiranverma is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I have the following legacy tables:
employee
------------------------------------
| employee_id | name
------------------------------------
| 1 | David
| 2 | Mathew
------------------------------------
payroll
-------------------------------------
| employee_id | salary
-------------------------------------
| 2 | 200000
| 3 | 90000
-------------------------------------
I want to get the following data, after joins and filters:
-----------------------------------------------------------
| address_id | employee_id | address
-----------------------------------------------------------
| 1 | 2 | street 1, NY
| 2 | 2 | street 2, DC
------------------------------------------------------------
I have the following query:
SELECT employee_id, salary, address_arr
FROM employee
LEFT JOIN payroll on payroll.employee_id = employee.employee_id
INNER JOIN
(
SELECT employee_id, ARRAY_AGG(address) as address_arr
FROM addresses
GROUP BY employee_id
) table_address ON table_address.employee_id = employee.employee_id
WHERE employee.employee_id < 1000000
LIMIT 100
OFFSET 0
Above query gives the desired output but is highly unoptimized as the GROUP BY operation occurs over the complete addresses table before being used for JOIN operation the outer query.
Kindly answer:
- How can we avoid the
GROUP BYoperation to occurs over the complete
addresses table by usingLIMIT OFFSETof the outer query? - Will the condition
WHERE employee.employee_id < 1000000be applied on subquery before or after theGROUP BYoperation in the inner query. If the condition is applied after theGROUP BY, how can we avoid that?
postgresql join postgresql-performance group-by subquery
postgresql join postgresql-performance group-by subquery
asked 2 mins ago
nimeshkiranvermanimeshkiranverma
1012
New contributor
nimeshkiranverma is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 2 mins ago
nimeshkiranvermanimeshkiranverma
1012
New contributor
nimeshkiranverma is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 2 mins ago
nimeshkiranvermanimeshkiranverma
1012
New contributor
nimeshkiranverma is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 2 mins ago
nimeshkiranvermanimeshkiranverma
1012
asked 2 mins ago
nimeshkiranvermanimeshkiranverma
1012
1012
New contributor
nimeshkiranverma is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
nimeshkiranverma is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
nimeshkiranverma is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
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